Answer:
At 3:30 p.m. she started playing the piano
Step-by-step explanation:
We are given the following information:
Marcy played the piano for 45 minutes.
She stopped playing at 4:15 p.m.
This means that at 3:30 p.m. she started playing the piano.
( since 15 minutes before 4:15 om is 4:00 pm now 30 minutes more before 4:00 pm is 3:30 pm which adds up to:
15+30=45 min.)